Contributor
Fascinating discussion, thank you!
So just so I am clear...a soft (inexpensive) cotton wheel is better than a hard felt wheel? I have the latter now (made in France it says, from LV) and I am better off getting a soft cotton wheel from HD or Amazon? My grinder is a regular speed 6” Craftsman model from years ago btw.
Thanks again.
Kevin
[OP]
Member
Kevin,Originally Posted by Kevin Adams
The folks that have tried hard wheels say it is easy to ruin an edge, that you are better off with a soft cotton wheels.
ken
Contributor
I've waded through much of the discussion on Wood Central....or tried to.
Just for clarification, the instructions have you go right from a 1000 grit stone to cotton buffing wheel. Would any steps inserted in between (additional honing) be considered unnecessary? Or detrimental to the process.?
[OP]
Member
Clifford,
Unnecessary. The goal of sharpening Unicorn or other ways is to have a strong and smooth cutting edge. The smoothness behind the cutting edge, within reason, makes little difference. Using a progression of stones is a waste of time, negating one of the reasons to use the Unicorn process.
ken
Contributor
Thanks, Ken, I found this one on Amazon and will give it a go:
https://www.amazon.com/gp/product/B0...PFZX1YUE&psc=1
Anyone try it on Japanese chisels or is that total sacrilege?!
Kevin
Contributor
What is the compound they are using on it? I have a green crayon from Lee Valley. Is that finer than what they are doing, coarser, or am I completely misunderstanding?
[OP]
Member
Kevin,
LOL, IIRC David has used it on Japanese chisels and it worked well. The only problem is after having learned to keep a flat bevel and preserve the definition between the soft iron and the hard steel it would seem to be a total sacrilege. But rumor has it that So does the same with the chisels he sharpens for clients.
I wouldn't worry about it.
ken
[OP]
Member
Nicholas,
Working from memory and I'm an OF so memory sucks but I think they are using 0.5 micron or maybe less compound on the buffing wheel. Also IIRC LV "Green Stuff" is listed as 0.5 microns.
ken
[OP]
Member
Kevin,
I just looked at the buffing wheel from Amazon and could not find the grit it is charged with. IIRC you want a compound that is 0.5 microns or less.
ken
Contributor
I'm using the stick from the Ryobi kit, which I think is probably about 1 micron. I also have used 1-micron green compound from McMaster-Carr, and it works well. David uses 5-micron yellow compound from McMaster-Carr, and he also gets good results.
More information about equipment here: https://chisel-test.netlify.app/#equipment
Contributor
Please notice the nuance of the language used, "It rounds the cutting edge very easily."
George does not say it always rounds the edge.
Many years ago one of my supervisors would lament about the "American mind" thinking if a little was good twice as much is twice as good.
It is the same with stropping on leather or a soft buffing wheel. With care either can improve the edge on a tool up to a point. With carelessness either can round the edge. The degree of rounding depends on the degree of carelessness.
So far my experiments have been 3 for 4. Though today's attempt on a gouge may not be a real test because they have a geometry that works well with a slightly rounded edge. The blade that needed to be reworked may have been left too long under the buffing wheel.
The other test on this may be time. How many times can honing on one coarse stone followed by buffing can an edge take before it needs to be reground?
So in reality, it is very easy to round over the cutting edge if one doesn't take care. This can also happen on a flat leather strop. That is known from first hand experience.
Too bad this method came to light after some heavy mortise chopping on a project. It would have been a possible test of the Unicorn edge to see if there was any great benefit. Though the edges on the chisels used seemed to hold up rather well with standard sharpening & stropping.
Gonna Need a Bigger Chisel.jpg
Mortising is pretty much cutting across end grain. The chisel is a 3/4" flat sided chisel. Notice the full shavings the chisel is making across the end grain with help from a mallet. This was done using the 'riding the bevel' method.
jtk
Last edited by Jim Koepke; 08-13-2020 at 7:00 PM.
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)
Contributor
David has been using 5 micron stuff because, I believe, it is cheap. The green stuff from Lee Valley works just fine according to my limited testing.
Contributor
I think that David was clear that he had used a larger grit (like say 5 micron), but I also think that other tests show that smaller works just fine. I think that the other video on Vimeo he used the white which I think is about 1 micron. I don't think that it matters much, but right about now, my brain is mush (been working long hours).
[OP]
Member
Andrew,
My guess is there is a lot of leeway. Wish I had an excuse like long hours at work for mush brain, although this week has been on the back side of the clock and that usually cost 10 or so IQ points. Whatever mine is just natural.
Good luck with your playing, let us know what you find out. I should be posting photos soon.
ken
Contributor
I use the 0.5 micron LV green compound because I have a few sticks of it. David uses a 5.0 micron stick of something or other because it cuts faster and that is what he has. I think that the amount of the buffing process determines the final edge. Paul Sellers does about 50 strokes to get what I might with 5 on a waterstone. Winston needs to hold the chisel to the strop longer on his drill-driven set up than I do, but I am using a half speed bench grinder. David gets to use a coarser grit on a full speed machine.
With regard Japanese chisels, I have not seen a reason to risk my good chisels yet. They are honed at 30 degrees and hold a great edge. The aim of the unicorn bevel is to create longevity (although it can also create sharpness quickly). I did, however, hone a pair of Japanese mortice chisels on the buffer, and this was on a 30 degree bevel. The edge sharpened up quite significantly, but I cannot comment yet on longevity.
Fujikawa mortice chisel paring Jacaranda.
Regards from Perth
Derek
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